A basketball is a spherical object designed for organized play, but the term “normal” is misleading because standard dimensions vary widely across different leagues and age groups. To define the correct size, one must identify the context of play, including the players’ gender, age, and the governing body of the competition. Differences in size and weight are calibrated to support the development of appropriate handling and shooting techniques for various player physiologies.
The Official Men’s Regulation Size (Size 7)
The standard ball size for competitive men’s basketball, including the National Basketball Association (NBA) and the National Collegiate Athletic Association (NCAA) men’s games, is designated as Size 7. This ball has an official circumference of 29.5 inches (74.9 centimeters). The required weight for a Size 7 ball is 22 ounces (623.7 grams), which contributes to momentum and trajectory control during shooting.
Inflation pressure is a specific factor in the ball’s performance, as it affects rebound height. For professional play, the ball is inflated to a pressure between 7.5 and 8.5 pounds per square inch (PSI), ensuring a consistent bounce when dropped from a set height. This combination of circumference, weight, and pressure makes the Size 7 basketball the largest and heaviest used in high-level competition, typically for male players aged 15 and older.
The Official Women’s Regulation Size (Size 6)
Official women’s leagues utilize a ball with reduced dimensions to accommodate the average hand size of female players, designated as Size 6. This size is mandatory for the Women’s National Basketball Association (WNBA), NCAA women’s college basketball, and for female players aged 12 and older. The Size 6 ball has a circumference of 28.5 inches (72.4 centimeters), making it one inch smaller than the men’s regulation ball.
The weight is also reduced compared to the men’s ball, weighing 20 ounces (567 grams). This reduction in size and mass allows players to grip the ball more securely and execute passing and shooting motions with greater control. Using a properly sized ball aids skill development by preventing players from compensating for an oversized ball with improper shooting form.
Understanding Other Common Sizes and Weight Standards
Beyond the two primary regulation sizes, smaller basketballs are used to facilitate the development of younger players. The next size down is Size 5, which measures 27.5 inches in circumference and weighs 17 ounces (482 grams), recommended for children aged 9 to 11. Playing with a ball too heavy for a child’s strength can lead to bad habits, such as pushing the ball with two hands or using a lobbing motion.
Even smaller sizes exist, such as Size 4 (25.5 inches, 14 ounces) for ages 5 to 8, and Size 3 (22 inches, 10 ounces), which is often a mini or novelty ball. These smaller dimensions ensure young athletes can practice the correct one-handed shooting technique without straining their muscles. Furthermore, the material of the ball, whether it is full-grain leather for indoor professional play or a composite material for amateur or outdoor courts, also affects its feel and adherence to official standards.